1. Field of the Invention
This invention relates to a lock mechanism for use in a tape player, and more particularly to a lock mechanism for use in a tape player to hold a loaded tape pack in a playback position or holding operating members in their respective operative positions or inoperative positions.
2. Description of the Prior Art
In a tape player, it is essential to provide a lock mechanism for holding a loaded tape pack in a playback position or holding operating members such as operating levers in respective operative or inoperative positions. Therefore, there have been proposed various lock mechanisms for tape players. These known lock mechanisms, however, have such disadvantages that their locking and releasing operations are not always effected smoothly. In this respect, the known mechanisms generally comprise a locking projection formed on a member to be locked, a hook portion formed on a lock member for engaging with and disengaging from the projection and a separate actuator for actuating an operating portion of the lock member. In such a construction, a considerable force is required for the actuator and a complicated structure is needed to reverse the direction of loads for carrying out locking and releasing, i.e., to apply downward force for locking and an upward force for releasing. To obviate the disadvantage involved in such a mechanism for applying forces in opposite directions, there has been proposed a reversing spring. In this case, however, the spring must have a considerable arm length, which makes the structure bulky and requires so large operating force that a shock is possibly caused at the time of locking and releasing. By this reason, there has been proposed a structure wherein the hook portion of the lock member has oppositely formed diagonal operating portions and the actuator has an engaging member engageable with the hook portion so that when the actuator is depressed, the engaging member acts on the diagonal operating portions to displace the lock member out of the retreating course of the engaging member for letting the member pass therethrough and to reset the lock member thereafter for engaging, at the hook portion thereof, with the engaging member after the member reaches the hook portion. In this case, however, it is essential to form the diagonal portions integrally with the lock member. Therefore, the structure is not suitable for use in such a case where the operating portion is required to be separately used, i.e., a case of automatic ejection. In addition, since it is so designed that the locking is effected by once displacing the hook portion and then resetting it, the desired locking cannot be attained if either one of the displacement and resetting cannot be effected perfectly. Thus, there cannot be guaranteed a reliability of the operation. Furthermore, the structure requires, in general, an operating stroke larger than a stroke necessary for locking, e.g., an overpush. Where the loads applied to the lock member by the fulcrum of the lock member and by the actuator member are in the same direction, when the lock member is inclined in a direction to attain complete locking, a considerable force is required for releasing in a thrusting direction while the locking is easily releasable in a relief direction. Thus, there is a possibility of misoperation.